1. Field of Invention
The invention relates to the field of image sensors, and in particular to the high-speed image capture capability of image sensors.
2. Description of Related Art
Current image sensors are not able to achieve high-speed image capturing capability due to the time needed to read each line of data in the image array in a progressive manner from top to bottom of the array. For example, if the frame rate of an image sensor is 30, it will take 1/30 of a second to reset (or read) from the first line to reset (read) the last line of the image sensor array. This will cause a fast moving image to blur.
A typical approach to address this issue adds a storage element inside each pixel of the sensor array. The data in all the pixels are simultaneously transferred to the storage elements and subsequently read out to achieve a high-speed shutter effect.
This approach has two major shortcomings. First, the increase in per pixel area due to the added storage element increases total die size and with it the cost. Second, the simultaneous switching of the entire array of pixels will introduce current and noise spikes and thereby degrade image quality. A need exists for a high-speed image capture apparatus which uses standard pixels and hence does not increase the per pixel area, and which alleviates large current spikes and noise.